Self-doped ohmic contacts for compound semiconductor devices

Abstract

A compound semiconductor device is manufactured by forming an III-nitride compound semiconductor device structure on a silicon-containing semiconductor substrate, the III-nitride compound semiconductor device structure including a GaN alloy on GaN and a channel region arising near an interface between the GaN alloy and the GaN. One or more silicon-containing insulating layers are formed on a surface of the III-nitride compound semiconductor device structure adjacent the GaN alloy, and a contact opening is formed which extends through the one or more silicon-containing insulating layers to at least the GaN alloy. A region of GaN is regrown in the contact opening, and the regrown region of GaN is doped exclusively with Si out-diffused from the one or more silicon-containing insulating layers to form an ohmic contact which is doped only with the Si out-diffused from the one or more silicon-containing insulating layers.

What is claimed is: 
     
       1. A method of manufacturing a compound semiconductor device, comprising:
 forming a III-nitride compound semiconductor device structure on a silicon-containing semiconductor substrate, the III-nitride compound semiconductor device structure including a GaN alloy on GaN and a channel region arising near an interface between the GaN alloy and the GaN; 
 forming a SiN layer on the III-nitride compound semiconductor device structure adjacent the GaN alloy, a first Si-containing dielectric layer on the SiN layer and a second Si-containing dielectric layer on the first Si-containing dielectric layer; 
 forming a contact opening which extends through the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer to at least the GaN alloy; 
 re-growing a region of GaN in the contact opening; and 
 doping the regrown region of GaN exclusively with Si out-diffused from one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer to form an ohmic contact which is doped only with the Si out-diffused from the one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer. 
 
     
     
       2. The method according to  claim 1 , wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer after an insulated gate of the compound semiconductor device is formed. 
     
     
       3. The method according to  claim 1 , wherein the regrown region of GaN protrudes outward from the contact opening beyond the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer. 
     
     
       4. The method according to  claim 1 , wherein the regrown region of GaN is thinner than the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer. 
     
     
       5. The method according to  claim 1 , wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer before a gate of the compound semiconductor device is formed in contact with the GaN alloy. 
     
     
       6. The method according to  claim 1 , wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer after a gate of the compound semiconductor device is formed in contact with the GaN alloy. 
     
     
       7. The method according to  claim 1 , wherein the contact opening extends into the GaN alloy so that the ohmic contact extends into the GaN alloy and is spaced apart from the GaN by a region of the GaN alloy. 
     
     
       8. The method according to  claim 1 , wherein the silicon-containing semiconductor substrate is a crystalline silicon substrate having a growth surface with a [111] crystal orientation on which the III-nitride compound semiconductor device structure is formed. 
     
     
       9. The method according to  claim 1 , wherein the silicon-containing semiconductor substrate is a crystalline silicon carbide substrate having a growth surface with a [100] crystal orientation on which the III-nitride compound semiconductor device structure is formed. 
     
     
       10. A method of manufacturing a compound semiconductor device, comprising:
 forming GaN on a silicon-containing semiconductor substrate and a GaN alloy on the GaN so that a channel region arises near an interface between the GaN alloy and the GaN; 
 forming a SiN layer on a side of the GaN alloy facing away from the GaN, a first Si-containing dielectric layer on the SiN layer and a second Si-containing dielectric layer on the first Si-containing dielectric layer; 
 forming a contact opening which extends through the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer to at least the GaN alloy; 
 re-growing a region of GaN in the contact opening; and 
 doping the regrown region of GaN exclusively with Si out-diffused from the one or more silicon-containing insulating layers to form an ohmic contact which is doped only with the Si out-diffused from the one or more silicon-containing insulating layers. 
 
     
     
       11. The method according to  claim 10 , wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer after an insulated gate of the compound semiconductor device is formed. 
     
     
       12. The method according to  claim 10 , wherein the regrown region of GaN protrudes outward from the contact opening beyond the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer. 
     
     
       13. The method according to  claim 10 , wherein the regrown region of GaN is thinner than the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer. 
     
     
       14. The method according to  claim 10 , wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer before a gate of the compound semiconductor device is formed in contact with the GaN alloy. 
     
     
       15. The method according to  claim 10 , wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more of the SiN layer, the first Si-containing dielectric layer and the second Si-containing dielectric layer after a gate of the compound semiconductor device is formed in contact with the GaN alloy. 
     
     
       16. The method according to  claim 10 , wherein the contact opening extends into the GaN alloy so that the ohmic contact extends into the GaN alloy and is spaced apart from the GaN by a region of the GaN alloy. 
     
     
       17. The method according to  claim 10 , wherein the silicon-containing semiconductor substrate is a crystalline silicon substrate having a growth surface with a [111] crystal orientation on which the GaN is formed. 
     
     
       18. The method according to  claim 10 , wherein the silicon-containing semiconductor substrate is a crystalline silicon carbide substrate having a growth surface with a [100] crystal orientation on which the GaN is formed. 
     
     
       19. A method of manufacturing a compound semiconductor device, comprising:
 forming a III-nitride compound semiconductor device structure on a silicon-containing semiconductor substrate, the III-nitride compound semiconductor device structure including a GaN alloy on GaN and a channel region arising near an interface between the GaN alloy and the GaN; 
 forming one or more silicon-containing insulating layers on the III-nitride compound semiconductor device structure adjacent the GaN alloy; 
 forming a contact opening which extends through the one or more silicon-containing insulating layers to at least the GaN alloy; 
 re-growing a region of GaN in the contact opening; and 
 doping the regrown region of GaN exclusively with Si out-diffused from the one or more silicon-containing insulating layers to form an ohmic contact which is doped only with the Si out-diffused from the one or more silicon-containing insulating layers, 
 wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more silicon-containing insulating layers after a gate of the compound semiconductor device is formed in contact with the GaN alloy. 
 
     
     
       20. A method of manufacturing a compound semiconductor device, comprising:
 forming GaN on a silicon-containing semiconductor substrate and a GaN alloy on the GaN so that a channel region arises near an interface between the GaN alloy and the GaN; 
 forming one or more silicon-containing insulating layers on a side of the GaN alloy facing away from the GaN; 
 forming a contact opening which extends through the one or more silicon-containing insulating layers to at least the GaN alloy; 
 re-growing a region of GaN in the contact opening; and 
 doping the regrown region of GaN exclusively with Si out-diffused from the one or more silicon-containing insulating layers to form an ohmic contact which is doped only with the Si out-diffused from the one or more silicon-containing insulating layers, 
 wherein the region of GaN is regrown in the contact opening and doped exclusively with Si out-diffused from the one or more silicon-containing insulating layers after a gate of the compound semiconductor device is formed in contact with the GaN alloy.